This invention relates to a nozzle for dispensing gasoline into motor vehicle fuel tanks, and more specifically relates to an interlock system to prevent the operation of the nozzle until the discharge spout of the nozzle is properly inserted into the vehicle fillpipe.
Current environmental regulations require that gasoline vapors displaced from a vehicle fuel tank during dispensing be recovered to prevent their escape into the atmosphere. As part of these requirments, it is foreseeable that an interlock system may be required to both prevent the dispensing of gasoline and the opening of the gasoline vapor recovery system until the vapor receiving system is properly in contact with the vehicle fuel tank. Even if such a requirement never materializes, it is still desirable to have such an interlock system to encourage the filling station operator to have the vapor receiving system properly in place against the fillpipe.
The prior art discloses many designs for such an interlock system. One common approach uses a mechanical linkage between the face seal of the vapor receiving system and the automatic shut-off system within the nozzle housing. This type of system tends to be rather complicated, and adds to the weight of the nozzle as well as to the cost of construction and maintenance. Other designs include a valve located within the discharge spout and connected to the vent line which leads to the automatic shut-off system in the nozzle housing. This valve is then connected to the vapor receiving system in such a manner that it is closed when the vapor receiving system is not in contact with the vehicle fillpipe, thereby preventing the dispensing of gasoline. This particular design in the prior art has a drawback in that the valve has been located in the discharge spout of the nozzle and accordingly has been exposed to the flow of gasoline through the nozzle. With this approach, both the valve and its actuating mechanism must be designed to withstand the hostile environment in which they are located.